diff options
Diffstat (limited to 'kernfs-kernfs_notify-must-be-usable-from-non-sleepable-contexts.patch')
| -rw-r--r-- | kernfs-kernfs_notify-must-be-usable-from-non-sleepable-contexts.patch | 262 |
1 files changed, 0 insertions, 262 deletions
diff --git a/kernfs-kernfs_notify-must-be-usable-from-non-sleepable-contexts.patch b/kernfs-kernfs_notify-must-be-usable-from-non-sleepable-contexts.patch deleted file mode 100644 index 83bacc342..000000000 --- a/kernfs-kernfs_notify-must-be-usable-from-non-sleepable-contexts.patch +++ /dev/null @@ -1,262 +0,0 @@ -Bugzilla: 1113805 -Upstream-status: queued for 3.16 -Delivered-To: jwboyer@gmail.com -Received: by 10.76.6.212 with SMTP id d20csp61002oaa; - Tue, 1 Jul 2014 13:41:10 -0700 (PDT) -X-Received: by 10.70.36.203 with SMTP id s11mr216865pdj.30.1404247270266; - Tue, 01 Jul 2014 13:41:10 -0700 (PDT) -Return-Path: <htejun@gmail.com> -Received: from bastion.fedoraproject.org (bastion02.fedoraproject.org. 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[207.38.225.25]) - by mx.google.com with ESMTPSA id q12sm39024393qad.40.2014.07.01.13.41.04 - for <multiple recipients> - (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); - Tue, 01 Jul 2014 13:41:05 -0700 (PDT) -Sender: Tejun Heo <htejun@gmail.com> -Date: Tue, 1 Jul 2014 16:41:03 -0400 -From: Tejun Heo <tj@kernel.org> -To: Greg Kroah-Hartman <gregkh@linuxfoundation.org> -Cc: Jens Axboe <axboe@kernel.dk>, "Michael S. Tsirkin" <mst@redhat.com>, - Christoph Hellwig <hch@lst.de>, Josh Boyer <jwboyer@fedoraproject.org>, - Rusty Russell <rusty@rustcorp.com.au>, - virtualization@lists.linux-foundation.org, - "Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>, - Brian Lane <bcl@redhat.com>, John McCutchan <john@johnmccutchan.com>, - Robert Love <rlove@rlove.org>, Eric Paris <eparis@parisplace.org> -Subject: [PATCH driver-core-linus] kernfs: kernfs_notify() must be useable - from non-sleepable contexts -Message-ID: <20140701204103.GA12459@htj.dyndns.org> -References: <CA+5PVA4h2hQJLrAm4eEZ8oUgGiAjq2y5eAyBcJWxK_FiQXnuQg@mail.gmail.com> - <20140629082637.GA23942@redhat.com> - <20140629193222.GA7030@lst.de> - <20140629204710.GB11100@redhat.com> - <53B07D48.60003@kernel.dk> - <20140630201741.GA20853@htj.dyndns.org> -MIME-Version: 1.0 -Content-Type: text/plain; charset=us-ascii -Content-Disposition: inline -In-Reply-To: <20140630201741.GA20853@htj.dyndns.org> -User-Agent: Mutt/1.5.23 (2014-03-12) -X-RedHat-Spam-Score: -2.31 (BAYES_00,DCC_REPUT_00_12,DKIM_SIGNED,DKIM_VALID,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_PASS) -X-Scanned-By: MIMEDefang 2.68 on 10.5.110.16 - -d911d9874801 ("kernfs: make kernfs_notify() trigger inotify events -too") added fsnotify triggering to kernfs_notify() which requires a -sleepable context. There are already existing users of -kernfs_notify() which invoke it from an atomic context and in general -it's silly to require a sleepable context for triggering a -notification. - -The following is an invalid context bug triggerd by md invoking -sysfs_notify() from IO completion path. - - BUG: sleeping function called from invalid context at kernel/locking/mutex.c:586 - in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1 - 2 locks held by swapper/1/0: - #0: (&(&vblk->vq_lock)->rlock){-.-...}, at: [<ffffffffa0039042>] virtblk_done+0x42/0xe0 [virtio_blk] - #1: (&(&bitmap->counts.lock)->rlock){-.....}, at: [<ffffffff81633718>] bitmap_endwrite+0x68/0x240 - irq event stamp: 33518 - hardirqs last enabled at (33515): [<ffffffff8102544f>] default_idle+0x1f/0x230 - hardirqs last disabled at (33516): [<ffffffff818122ed>] common_interrupt+0x6d/0x72 - softirqs last enabled at (33518): [<ffffffff810a1272>] _local_bh_enable+0x22/0x50 - softirqs last disabled at (33517): [<ffffffff810a29e0>] irq_enter+0x60/0x80 - CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.16.0-0.rc2.git2.1.fc21.x86_64 #1 - Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 - 0000000000000000 f90db13964f4ee05 ffff88007d403b80 ffffffff81807b4c - 0000000000000000 ffff88007d403ba8 ffffffff810d4f14 0000000000000000 - 0000000000441800 ffff880078fa1780 ffff88007d403c38 ffffffff8180caf2 - Call Trace: - <IRQ> [<ffffffff81807b4c>] dump_stack+0x4d/0x66 - [<ffffffff810d4f14>] __might_sleep+0x184/0x240 - [<ffffffff8180caf2>] mutex_lock_nested+0x42/0x440 - [<ffffffff812d76a0>] kernfs_notify+0x90/0x150 - [<ffffffff8163377c>] bitmap_endwrite+0xcc/0x240 - [<ffffffffa00de863>] close_write+0x93/0xb0 [raid1] - [<ffffffffa00df029>] r1_bio_write_done+0x29/0x50 [raid1] - [<ffffffffa00e0474>] raid1_end_write_request+0xe4/0x260 [raid1] - [<ffffffff813acb8b>] bio_endio+0x6b/0xa0 - [<ffffffff813b46c4>] blk_update_request+0x94/0x420 - [<ffffffff813bf0ea>] blk_mq_end_io+0x1a/0x70 - [<ffffffffa00392c2>] virtblk_request_done+0x32/0x80 [virtio_blk] - [<ffffffff813c0648>] __blk_mq_complete_request+0x88/0x120 - [<ffffffff813c070a>] blk_mq_complete_request+0x2a/0x30 - [<ffffffffa0039066>] virtblk_done+0x66/0xe0 [virtio_blk] - [<ffffffffa002535a>] vring_interrupt+0x3a/0xa0 [virtio_ring] - [<ffffffff81116177>] handle_irq_event_percpu+0x77/0x340 - [<ffffffff8111647d>] handle_irq_event+0x3d/0x60 - [<ffffffff81119436>] handle_edge_irq+0x66/0x130 - [<ffffffff8101c3e4>] handle_irq+0x84/0x150 - [<ffffffff818146ad>] do_IRQ+0x4d/0xe0 - [<ffffffff818122f2>] common_interrupt+0x72/0x72 - <EOI> [<ffffffff8105f706>] ? native_safe_halt+0x6/0x10 - [<ffffffff81025454>] default_idle+0x24/0x230 - [<ffffffff81025f9f>] arch_cpu_idle+0xf/0x20 - [<ffffffff810f5adc>] cpu_startup_entry+0x37c/0x7b0 - [<ffffffff8104df1b>] start_secondary+0x25b/0x300 - -This patch fixes it by punting the notification delivery through a -work item. This ends up adding an extra pointer to kernfs_elem_attr -enlarging kernfs_node by a pointer, which is not ideal but not a very -big deal either. If this turns out to be an actual issue, we can move -kernfs_elem_attr->size to kernfs_node->iattr later. - -Signed-off-by: Tejun Heo <tj@kernel.org> -Reported-by: Josh Boyer <jwboyer@fedoraproject.org> -Cc: "Michael S. Tsirkin" <mst@redhat.com> -Cc: Jens Axboe <axboe@kernel.dk> ---- - fs/kernfs/file.c | 69 +++++++++++++++++++++++++++++++++++++++---------- - include/linux/kernfs.h | 1 - 2 files changed, 56 insertions(+), 14 deletions(-) - ---- a/fs/kernfs/file.c -+++ b/fs/kernfs/file.c -@@ -39,6 +39,19 @@ struct kernfs_open_node { - struct list_head files; /* goes through kernfs_open_file.list */ - }; - -+/* -+ * kernfs_notify() may be called from any context and bounces notifications -+ * through a work item. To minimize space overhead in kernfs_node, the -+ * pending queue is implemented as a singly linked list of kernfs_nodes. -+ * The list is terminated with the self pointer so that whether a -+ * kernfs_node is on the list or not can be determined by testing the next -+ * pointer for NULL. -+ */ -+#define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list) -+ -+static DEFINE_SPINLOCK(kernfs_notify_lock); -+static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL; -+ - static struct kernfs_open_file *kernfs_of(struct file *file) - { - return ((struct seq_file *)file->private_data)->private; -@@ -783,24 +796,25 @@ static unsigned int kernfs_fop_poll(stru - return DEFAULT_POLLMASK|POLLERR|POLLPRI; - } - --/** -- * kernfs_notify - notify a kernfs file -- * @kn: file to notify -- * -- * Notify @kn such that poll(2) on @kn wakes up. -- */ --void kernfs_notify(struct kernfs_node *kn) -+static void kernfs_notify_workfn(struct work_struct *work) - { -- struct kernfs_root *root = kernfs_root(kn); -+ struct kernfs_node *kn; - struct kernfs_open_node *on; - struct kernfs_super_info *info; -- unsigned long flags; -- -- if (WARN_ON(kernfs_type(kn) != KERNFS_FILE)) -+repeat: -+ /* pop one off the notify_list */ -+ spin_lock_irq(&kernfs_notify_lock); -+ kn = kernfs_notify_list; -+ if (kn == KERNFS_NOTIFY_EOL) { -+ spin_unlock_irq(&kernfs_notify_lock); - return; -+ } -+ kernfs_notify_list = kn->attr.notify_next; -+ kn->attr.notify_next = NULL; -+ spin_unlock_irq(&kernfs_notify_lock); - - /* kick poll */ -- spin_lock_irqsave(&kernfs_open_node_lock, flags); -+ spin_lock_irq(&kernfs_open_node_lock); - - on = kn->attr.open; - if (on) { -@@ -808,12 +822,12 @@ void kernfs_notify(struct kernfs_node *k - wake_up_interruptible(&on->poll); - } - -- spin_unlock_irqrestore(&kernfs_open_node_lock, flags); -+ spin_unlock_irq(&kernfs_open_node_lock); - - /* kick fsnotify */ - mutex_lock(&kernfs_mutex); - -- list_for_each_entry(info, &root->supers, node) { -+ list_for_each_entry(info, &kernfs_root(kn)->supers, node) { - struct inode *inode; - struct dentry *dentry; - -@@ -833,6 +847,33 @@ void kernfs_notify(struct kernfs_node *k - } - - mutex_unlock(&kernfs_mutex); -+ kernfs_put(kn); -+ goto repeat; -+} -+ -+/** -+ * kernfs_notify - notify a kernfs file -+ * @kn: file to notify -+ * -+ * Notify @kn such that poll(2) on @kn wakes up. Maybe be called from any -+ * context. -+ */ -+void kernfs_notify(struct kernfs_node *kn) -+{ -+ static DECLARE_WORK(kernfs_notify_work, kernfs_notify_workfn); -+ unsigned long flags; -+ -+ if (WARN_ON(kernfs_type(kn) != KERNFS_FILE)) -+ return; -+ -+ spin_lock_irqsave(&kernfs_notify_lock, flags); -+ if (!kn->attr.notify_next) { -+ kernfs_get(kn); -+ kn->attr.notify_next = kernfs_notify_list; -+ kernfs_notify_list = kn; -+ schedule_work(&kernfs_notify_work); -+ } -+ spin_unlock_irqrestore(&kernfs_notify_lock, flags); - } - EXPORT_SYMBOL_GPL(kernfs_notify); - ---- a/include/linux/kernfs.h -+++ b/include/linux/kernfs.h -@@ -91,6 +91,7 @@ struct kernfs_elem_attr { - const struct kernfs_ops *ops; - struct kernfs_open_node *open; - loff_t size; -+ struct kernfs_node *notify_next; /* for kernfs_notify() */ - }; - - /* |